Transparent articles and methods of making transparent articles

Abstract

A method of making a transparent article includes mixing an oxygen source, a nitrogen source, a magnesium source, a silicon source and a calcium source. The oxygen source, the nitrogen source, the magnesium source, the silicon source, and the calcium source are milled and heated to form a molten oxynitride glass modified by calcium and magnesium. The molten oxynitride glass modified by calcium and magnesium is then cooled to form a transparent body having ballistic resistance with a level of performance satisfying Level IV of National Institute of Justice Standard 0108.01. Transparent articles having transparent bodies formed from the oxynitride glass are also described.

What is claimed is: 
     
         1 . A method of making a transparent article, comprising:
 mixing an oxygen source, a nitrogen source, a magnesium source, a silicon source and a calcium source;   heating the oxygen source, the nitrogen source, the magnesium source, the silicon source, and the calcium source to form a molten oxynitride glass modified by calcium and magnesium; and   cooling the molten oxynitride glass modified by calcium and magnesium to solidify the molten oxynitride glass as a transparent body,   wherein the transparent body has ballistic resistance such that armor piercing test ammunition having a bullet mass of 166 grains fired from a barrel having a 22 inch length and traveling at a velocity of about 2850 feet per second does not penetrate the transparent body when tested in compliance with Level IV of National Institute of Justice Standard 0108.01, September 1985   
     
     
         2 . The method as recited in  claim 1 , wherein the nitrogen source is silicon dioxide, wherein the calcium source is a second nitrogen source, and wherein the magnesium source is a third nitrogen source. 
     
     
         3 . The method as recited in  claim 1 , wherein the magnesium source includes magnesium nitride. 
     
     
         4 . The method as recited in  claim 1 , wherein the magnesium source includes magnesium oxide. 
     
     
         5 . The method as recited in  claim 4 , wherein the magnesium source excludes magnesium hydride. 
     
     
         6 . The method as recited in  claim 4 , wherein the magnesium source includes at least one of magnesium nitride, magnesium oxide, magnesium silicate, and magnesium carbonate. 
     
     
         7 . The method as recited in  claim 1 , wherein the magnesium source consists essentially of magnesium nitride. 
     
     
         8 . The method as recited in  claim 1 , wherein the magnesium source consists essentially of magnesium oxide. 
     
     
         9 . The method as recited in  claim 1 , wherein the magnesium source consists essentially of magnesium nitride and magnesium oxide. 
     
     
         10 . The method as recited in  claim 1 , wherein the magnesium source includes magnesium silicate. 
     
     
         11 . The method as recited in  claim 1 , wherein the magnesium source consists essentially of magnesium silicate. 
     
     
         12 . The method as recited in  claim 1 , further comprising milling the oxygen source, the nitrogen source, the magnesium source, the silicon source, and the calcium source. 
     
     
         13 . The method as recited in  claim 12 , wherein milling includes anhydrously milling the oxygen, nitrogen, magnesium and calcium sources, wherein heating the milled oxygen, nitrogen, magnesium and calcium sources includes heating the sources in a nitrogen atmosphere with a pressure of less than 1 atmosphere. 
     
     
         14 . The method as recited in  claim 1 , further comprising:
 reheating the transparent body; and   dimensioning the re-heated transparent body by slumping the re-heated transparent body over an arcuate contour of a mandrel.   
     
     
         15 . The method as recited in  claim 1 , wherein heating includes heating the transparent body to between about 1600 and 1700 degrees Celsius, wherein re-heating includes re-heating the transparent body to between about 600 and 1000 degrees Celsius. 
     
     
         16 . A transparent article, comprising:
 a transparent body including oxynitride glass; and   magnesium and calcium modifying the oxynitride glass, wherein the transparent body has a ballistic resistance such that armor piercing test ammunition having a bullet mass of 166 grains fired from a barrel having a 22 inch length and traveling at a velocity of about 2850 feet per second does not penetrate the transparent body when tested in compliance with Level IV of National Institute of Justice Standard 0108.01, September 1985.   
     
     
         17 . The transparent article as recited in  claim 16 , wherein the transparent body has dimensioning approximating that of an aircraft windscreen. 
     
     
         18 . The transparent article as recited in  claim 16 , wherein the oxynitride glass excludes aluminum. 
     
     
         19 . The transparent article as recited in  claim 16 , wherein the oxynitride glass comprises oxygen, nitrogen, magnesium, silicon, and calcium. 
     
     
         20 . The transparent article as recited in  claim 16 , wherein the oxynitride glass consists essentially of oxygen, nitrogen, magnesium, silicon, and calcium. 
     
     
         21 . The transparent article as recited in  claim 16 , wherein the oxynitride glass has between about 30 to 50 atomic percent oxygen. 
     
     
         22 . The transparent article as recited in  claim 16 , wherein the oxynitride glass has between about 10 to 30 atomic percent nitrogen. 
     
     
         23 . The transparent article as recited in  claim 16 , wherein the oxynitride glass has between about 10 to 30 atomic percent silicon. 
     
     
         24 . The transparent article as recited in  claim 16 , wherein the oxynitride glass comprises substantially none to about 25 atomic percent magnesium and between about 10 to 30 atomic percent calcium. 
     
     
         25 . The transparent article as recited in  claim 16 , wherein the oxynitride glass comprises between about 30 to 50 atomic percent oxygen, 10 to 30 atomic percent nitrogen, 10 to 30 atomic percent silicon, substantially none to 25 atomic percent magnesium, and 10 to 30 atomic percent calcium. 
     
     
         26 . The transparent article as recited in  claim 16 , wherein the oxynitride glass comprises between about 35 to 40 atomic percent oxygen, 15 to 25 atomic percent nitrogen, 19 to 23 atomic percent silicon, 2 to 10 atomic percent magnesium, and 14 to 20 atomic percent calcium. 
     
     
         27 . The transparent article as recited in  claim 16 , wherein the oxynitride glass comprises between about 36 to 39 atomic percent oxygen, 17 to 19 atomic percent nitrogen, about 21 atomic percent silicon, about 5.5 atomic percent magnesium, and about 17.5 atomic percent calcium. 
     
     
         28 . The transparent article as recited in  claim 16 , wherein the transparent body has strike and opposite backing faces, one of the strike and backing faces being an as-melted surface. 
     
     
         29 . The transparent article as recited in  claim 16 , wherein the transparent body has a profile with an arcuate segment, wherein the as-melted surface defines the arcuate segment of the profile. 
     
     
         30 . The transparent article as recited in  claim 16 , wherein the transparent body has a strike face and an opposed backing face, at least one of the strike and backing faces being an as-melted surface. 
     
     
         31 . The transparent article as recited in  claim 30 , wherein the transparent body has a profile with an arcuate segment, wherein the unpolished surface defines the arcuate segment of the profile. 
     
     
         32 . The transparent article as recited in  claim 16 , wherein the transparent body has a profile with an arcuate segment, wherein the profile is bounded by an as-melted surface segment and a ground surface segment. 
     
     
         33 . The transparent article of  claim 16 , wherein the transparent body is has dimensioning corresponding to that of a window, a screen, a canopy, or a dome. 
     
     
         34 . An armor window for an aircraft, comprising:
 a transparent article as recited in  claim 16 ,   wherein the oxynitride glass comprises between about 36 and about 39 atomic percent oxygen, between about 17 and about 19 atomic percent nitrogen, about 21 atomic percent silicon, about 5.5 atomic percent magnesium, and about 17.5 atomic percent calcium,   wherein the transparent body has a strike face and an opposed backing face, wherein the strike face has an arcuate profile and an as-melted surface in a finished state, wherein the backing face has an arcuate profile that is ground or polished in the finished state.